Musical sounds may be generally classified in terms of rhythm and pitch. The pitch of a musical sound is determined by the frequency of the sound wave produced by a musical instrument. The difference in pitch between a sound wave having a frequency “f” and a sound wave having a frequency “2f” is termed an “octave”.
There are twelve identifiable notes that may be identified using the first seven letters of the alphabet (i.e., “A” through “G”). When these twelve notes repeat themselves in either a higher or lower pitch an octave is reached. For example, if all twelve notes are played in order beginning with the note “C,” one complete octave will have been played when either the next higher or next lower “C” note is reached. With reference to Chart 1, the next note after “B” is “C,” which is the beginning of the next octave. Thus, a change of one octave is achieved by moving from any one note, up or down, to the next note of the same name (e.g., A to A, B to B, C to C, etc) which is the beginning of the next octave.
The term “octave” (meaning 8 notes) appears to be a misnomer, since an octave actually comprises 12 notes. However, even though there are twelve identifiable notes in an octave, only seven of these twelve “semitones” or half steps are used. These seven notes make up what is termed a musical “key” or “scale”. When an individual plays in a musical key using these seven notes, the “eighth” note is an octave above or below one of the seven notes in that key. These musical keys are built upon musical patterns or formulas using a sequence of tones (whole steps) and semitones (half steps).
As mentioned previously, an octave is subdivided into twelve notes called semitones which, when played in succession, comprise a chromatic scale. This is illustrated by Chart 1.

The difference in pitch, or the interval spanning two semitones, is called a “tone”, or whole step, and the sequences of tones and semitones characterize a variety of non-chromatic scales such as the major, harmonic minor and melodic minor scales. The ascending major scale, for example, is characterized by the succession of two tones, one semitone, three more tones and one more semitone. The scale can also be described in terms of two tetra chords of two tones followed by one semitone, wherein the two tetra chords are separated by a tone. The ascending harmonic minor scale, however, is characterized by one tone, one semitone, two more tones, one more semitone, one and a half tones and a final semitone. Each note of the scale is described by a letter A through G and sharps (“#”) and flats (“music-flat”) are used to describe the semitones that fall between those letters. For example, the interval between A and B is one tone, the semitone above A is A# but can alternatively be described as the semitone below B, or B.music-flat.
Whether a scale will contain certain sharps or flats depends on what the first, “tonic”, or base note, of the scale is. For a major scale, the tonic is C and the scale is said to be in the “key of C major.” In the key of C major there are no sharps or flats. However, if the tonic is “C sharp”, i.e., C# major key, there are seven sharps. If the tonic is “C flat”, i.e., C.music-flat. major key, there are seven flats.
It can be very difficult for a student, and sometimes even a music teacher, to determine the correct notes of a certain type of scale in a certain key. It becomes even more difficult to rewrite or “transpose” music that has been written in one key into another key. For example, the ascending “C major” scale is C, D, E, F, G, A, B, C. Transposing it to “D major” is not simply a matter of replacing each note with the next letter in sequence because that will not preserve the sequence of tones and semi-tones that characterize a major scale. That is, D major is not D, E, F, G, A, B, C, D, but rather D, E, F#, G, A, B, C#, D so as to conform to the correct placement of tones' and semitones for major scale construction as described above.
Most beginners in the field of music have difficulty in grasping the fundamental concepts behind the organization of musical scale structures. As a result, the teaching of music can quickly become tedious and frustrating both for the pupil and the teacher. Various types of aids have been devised to help students to better understand music theory. Example teaching aids include charts, tables, graphs, computer programs and slide rules. However, these aids suffer from drawbacks that limit their effectiveness. For example, students can be easily confused and intimidated by the complex array of letters and symbols displayed by the various aids. These devices generally require that the student already possess a detailed knowledge of music theory to be able to use them effectively. In addition, current aids are not easily usable in conjunction with musical instruments, requiring the user to operate either the instrument or the aid, but not both at the same time. This limits the effectiveness of the music aid for such tasks as transposing music. There is a need for a music learning aid that is not intimidating and is easy to use. There is a further need for a music learning aid that is of a convenient size and shape, and can be used in conjunction with a variety of musical instruments. There is still further need to have a music aid that can be employed by the musician concurrently while they are playing their instrument.